Feature Request: Templatize `dataUrl` and `footer`

[IAmHughes]

Problem Statement

When running Hubble on-prem, we have to manually update two places in the code every time we pull the latest from this repository into our own private fork, either rebasing this change onto the head of the official Autodesk/hubble repo or submitting an additional commit every time to update our files below.

1. In hubble/docs/_config.yml to update our dataUrl:

dataURL: https://autodesk.github.io/hubble/demo-data

2. In hubble/docs/_includes/footer.html for the support footer information:

Statistics are maintained by the <a href="mailto:YOUR-EMAIL@COMPANY.com?Subject=Hubble%20Enterprise%20Feedback" target="_top"">Source Control Solutions team</a>.

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Is it possible that the solution is as simple as this repository providing a _config.yml.example so that it doesn't replace our local _config.yml every time we fetch the latest from this repository and merge it to our local copy on prem? Another possible option may be leveraging the GET repository secrets API.

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@larsxschneider @pluehne as I know you're familiar with the problem statement I'm calling out above, perhaps this can be a good pair session to hack out together?